There is no real difference, save that, color is American spelling and colour is British spelling. The thing is that Americans negate silent letters and make the words more exact in account to spelling and pronunciation, in order to make English friendlier and different from the British. Eg: Honor (American) and Honour (British): Organise (American) : Organize (British): Program (American) , Programme (British)

"Color" is the accepted U.S. spelling, "Colour" British. There are many such pairs. https://en.wikipedia.org/wiki/American_and_British_English_spelling_differences has a long article about them. Many of them originated with a specific lexicographer (dictionary author), Noah Webster, who authored some very popular school textbooks and a dictionary in the early 1800s. For some reason he decided to simplify some spellings and make them more phonetic, and he became an accepted authority. You should make a slight effort to figure out whether your English textbooks are using U.S. or British spellings, and try to stick to whichever your instructors are using. Nowadays most computers will check spelling--even when you are not using a word processor--and most will let you select U.S. or U.K. English. In this posting, my computer has underlined the word "Colour" in red, because it is not considered a correct spelling in the U.S. Everyone in both countries understands the others' spelling and vocabulary--usually. Sometimes people don't even notice the difference, such as "traveler" versus "traveller" or "judgment" versus "judgement."

All the same. Color, labor, center, honor, flavor - American spelling. Colour, labour, centre, honour, flavour - British spelling.